//<p>给定一个二叉树，找出其最小深度。</p>
//
//<p>最小深度是从根节点到最近叶子节点的最短路径上的节点数量。</p>
//
//<p><strong>说明：</strong>叶子节点是指没有子节点的节点。</p>
//
//<p> </p>
//
//<p><strong>示例 1：</strong></p>
//<img alt="" src="https://assets.leetcode.com/uploads/2020/10/12/ex_depth.jpg" style="width: 432px; height: 302px;" />
//<pre>
//<strong>输入：</strong>root = [3,9,20,null,null,15,7]
//<strong>输出：</strong>2
//</pre>
//
//<p><strong>示例 2：</strong></p>
//
//<pre>
//<strong>输入：</strong>root = [2,null,3,null,4,null,5,null,6]
//<strong>输出：</strong>5
//</pre>
//
//<p> </p>
//
//<p><strong>提示：</strong></p>
//
//<ul>
//	<li>树中节点数的范围在 <code>[0, 10<sup>5</sup>]</code> 内</li>
//	<li><code>-1000 <= Node.val <= 1000</code></li>
//</ul>
//<div><div>Related Topics</div><div><li>树</li><li>深度优先搜索</li><li>广度优先搜索</li><li>二叉树</li></div></div><br><div><li>👍 656</li><li>👎 0</li></div>
  
package leetcode.editor.cn;

public class _111_MinimumDepthOfBinaryTree{
    public static void main(String[] args) {
         Solution solution = new _111_MinimumDepthOfBinaryTree().new Solution();
    }
    //leetcode submit region begin(Prohibit modification and deletion)
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Solution {
    public int minDepth(TreeNode root) {
        if (root == null) {
            return 0;
        }
        if (root.left==null && root.right==null) {
            return 1;
        }
        int left = minDepth(root.left);
        int right = minDepth(root.right);
        if (root.left==null || root.right==null) {
            return left+right+1;
        }
        return Math.min(left, right)+1;
    }
}
//leetcode submit region end(Prohibit modification and deletion)

}